更新了数据库部分的文档和代码

Day36-40/36-38.关系型数据库MySQL.md

@@ -1081,7 +1081,7 @@ drop procedure sp_score_by_cid;
 
    - 检查约束（check）
 
-     > 说明：在MySQL数据库中，检查约束并不起作用。
+     > **说明**：在MySQL数据库中，检查约束并不起作用。
 
 #### 数据一致性
 

Day36-40/code/HRS_create_and_init.sql

@@ -1,11 +1,8 @@
 drop database if exists hrs;
-create database hrs default charset utf8mb4 collate utf8_bin;
+create database hrs default charset utf8mb4;
 
 use hrs;
 
-drop table if exists tb_emp;
-drop table if exists tb_dept;
-
 create table tb_dept
 (
 dno int not null comment '编号',
@@ -14,8 +11,6 @@ dloc varchar(20) not null comment '所在地',
 primary key (dno)
 );
 
--- alter table tb_dept add constraint pk_dept_dno primary key(dno);
-
 insert into tb_dept values 
     (10, '会计部', '北京'),
     (20, '研发部', '成都'),

Day36-40/code/SRS_create_and_init.sql

@@ -1,80 +1,83 @@
 -- 如果存在名为school的数据库就删除它
-drop database if exists school;
+drop database if exists `school`;
 
 -- 创建名为school的数据库并设置默认的字符集和排序方式
-create database school default charset utf8mb4;
+create database `school` default charset utf8mb4;
 
 -- 切换到school数据库上下文环境
-use school;
+use `school`;
 
 -- 创建学院表
-create table tb_college
+create table `tb_college`
 (
-collid 		int auto_increment comment '编号',
+`col_id` int unsigned auto_increment comment '编号',
-collname 	varchar(50) not null comment '名称',
+`col_name` varchar(50) not null comment '名称',
-collintro 	varchar(500) default '' comment '介绍',
+`col_intro` varchar(5000) default '' comment '介绍',
-primary key (collid)
+primary key (`col_id`)
-);
+) engine=innodb;
 
 -- 创建学生表
-create table tb_student
+create table `tb_student`
 (
-stuid 		int not null comment '学号',
+`stu_id` int unsigned not null comment '学号',
-stuname 	varchar(20) not null comment '姓名',
+`stu_name` varchar(20) not null comment '姓名',
-stusex 		boolean default 1 comment '性别',
+`stu_sex` boolean default 1 comment '性别',
-stubirth 	date not null comment '出生日期',
+`stu_birth` date not null comment '出生日期',
-stuaddr 	varchar(255) default '' comment '籍贯',
+`stu_addr` varchar(255) default '' comment '籍贯',
-collid 		int not null comment '所属学院',
+`col_id` int unsigned not null comment '所属学院',
-primary key (stuid),
+primary key (`stu_id`),
-foreign key (collid) references tb_college (collid)
+foreign key (`col_id`) references `tb_college` (`col_id`)
-);
+) engine=innodb;
 
 -- 创建教师表
-create table tb_teacher
+create table `tb_teacher`
 (
-teaid 		int not null comment '工号',
+`tea_id` int unsigned not null comment '工号',
-teaname 	varchar(20) not null comment '姓名',
+`tea_name` varchar(20) not null comment '姓名',
-teatitle 	varchar(10) default '讲师' comment '职称',
+`tea_title` varchar(10) default '助教' comment '职称',
-collid 		int not null comment '所属学院',
+`col_id` int unsigned not null comment '所属学院',
-primary key (teaid),
+primary key (`tea_id`),
-foreign key (collid) references tb_college (collid)
+foreign key (`col_id`) references `tb_college` (`col_id`)
 );
 
 -- 创建课程表
-create table tb_course
+create table `tb_course`
 (
-couid 		int not null comment '编号',
+`cou_id` int unsigned not null comment '编号',
-couname 	varchar(50) not null comment '名称',
+`cou_name` varchar(50) not null comment '名称',
-coucredit 	int not null comment '学分',
+`cou_credit` int unsigned not null comment '学分',
-teaid 		int not null comment '授课老师',
+`tea_id` int unsigned not null comment '授课老师',
-primary key (couid),
+primary key (`cou_id`),
-foreign key (teaid) references tb_teacher (teaid)
+foreign key (`tea_id`) references `tb_teacher` (`tea_id`)
 );
 
 -- 创建选课记录表
-create table tb_record
+create table `tb_record`
 (
-recid 		int auto_increment comment '选课记录编号',
+`rec_id` bigint unsigned auto_increment comment '选课记录号',
-sid 		int not null comment '选课学生',
+`sid` int unsigned not null comment '学号',
-cid 		int not null comment '所选课程',
+`cid` int unsigned not null comment '课程编号',
-seldate 	datetime default now() comment '选课时间日期',
+`sel_date` date not null comment '选课日期',
-score 		decimal(4,1) comment '考试成绩',
+`score` decimal(4,1) comment '考试成绩',
-primary key (recid),
+primary key (`rec_id`),
-foreign key (sid) references tb_student (stuid),
+foreign key (`sid`) references `tb_student` (`stu_id`),
-foreign key (cid) references tb_course (couid),
+foreign key (`cid`) references `tb_course` (`cou_id`),
-unique (sid, cid)
+unique (`sid`, `cid`)
 );
 
 -- 插入学院数据
-insert into tb_college (collname, collintro) values 
+insert into `tb_college` 
+    (`col_name`, `col_intro`) 
+values 
     ('计算机学院', '计算机学院1958年设立计算机专业，1981年建立计算机科学系，1998年设立计算机学院，2005年5月，为了进一步整合教学和科研资源，学校决定，计算机学院和软件学院行政班子合并统一运作、实行教学和学生管理独立运行的模式。 学院下设三个系：计算机科学与技术系、物联网工程系、计算金融系；两个研究所：图象图形研究所、网络空间安全研究院（2015年成立）；三个教学实验中心：计算机基础教学实验中心、IBM技术中心和计算机专业实验中心。'),
     ('外国语学院', '外国语学院设有7个教学单位，6个文理兼收的本科专业；拥有1个一级学科博士授予点，3个二级学科博士授予点，5个一级学科硕士学位授权点，5个二级学科硕士学位授权点，5个硕士专业授权领域，同时还有2个硕士专业学位（MTI）专业；有教职员工210余人，其中教授、副教授80余人，教师中获得中国国内外名校博士学位和正在职攻读博士学位的教师比例占专任教师的60%以上。'),
     ('经济管理学院', '经济学院前身是创办于1905年的经济科；已故经济学家彭迪先、张与九、蒋学模、胡寄窗、陶大镛、胡代光，以及当代学者刘诗白等曾先后在此任教或学习。');
 
 -- 插入学生数据
-insert into tb_student (stuid, stuname, stusex, stubirth, stuaddr, collid) 
+insert into `tb_student` 
+    (`stu_id`, `stu_name`, `stu_sex`, `stu_birth`, `stu_addr`, `col_id`) 
 values
-    (1001, '杨逍', 1, '1990-3-4', '四川成都', 1),
+    (1001, '杨过', 1, '1990-3-4', '湖南长沙', 1),
     (1002, '任我行', 1, '1992-2-2', '湖南长沙', 1),
     (1033, '王语嫣', 0, '1989-12-3', '四川成都', 1),
     (1572, '岳不群', 1, '1993-7-19', '陕西咸阳', 1),
@@ -83,17 +86,12 @@ values
     (2035, '东方不败', 1, '1988-6-30', null, 2),
     (3011, '林震南', 1, '1985-12-12', '福建莆田', 3),
     (3755, '项少龙', 1, '1993-1-25', null, 3),
-    (3923, '杨不悔', 0, '1985-4-17', '四川成都', 3),
+    (3923, '杨不悔', 0, '1985-4-17', '四川成都', 3);
-    (4040, '炼腰的隔壁老王', 1, '1989-1-1', '四川成都', 2);
-
--- 删除学生数据
-delete from tb_student where stuid=4040;
-
--- 更新学生数据
-update tb_student set stuname='杨过', stuaddr='湖南长沙' where stuid=1001;
 
 -- 插入老师数据
-insert into tb_teacher (teaid, teaname, teatitle, collid) values 
+insert into `tb_teacher` 
+    (`tea_id`, `tea_name`, `tea_title`, `col_id`) 
+values 
     (1122, '张三丰', '教授', 1),
     (1133, '宋远桥', '副教授', 1),
     (1144, '杨逍', '副教授', 1),
@@ -101,7 +99,9 @@ insert into tb_teacher (teaid, teaname, teatitle, collid) values
     (3366, '韦一笑', default, 3);
 
 -- 插入课程数据
-insert into tb_course (couid, couname, coucredit, teaid) values 
+insert into `tb_course` 
+    (`cou_id`, `cou_name`, `cou_credit`, `tea_id`) 
+values 
     (1111, 'Python程序设计', 3, 1122),
     (2222, 'Web前端开发', 2, 1122),
     (3333, '操作系统', 4, 1122),
@@ -113,7 +113,9 @@ insert into tb_course (couid, couname, coucredit, teaid) values
     (9999, '审计学', 3, 3366);
 
 -- 插入选课数据
-insert into tb_record (sid, cid, seldate, score) values 
+insert into `tb_record` 
+    (`sid`, `cid`, `sel_date`, `score`) 
+values 
     (1001, 1111, '2017-09-01', 95),
     (1001, 2222, '2017-09-01', 87.5),
     (1001, 3333, '2017-09-01', 100),
@@ -128,116 +130,7 @@ insert into tb_record (sid, cid, seldate, score) values
     (1378, 1111, '2017-09-05', 82),
     (1378, 7777, '2017-09-02', 65.5),
     (2035, 7777, '2018-09-03', 88),
-(2035, 9999, default, null),
+    (2035, 9999, '2019-09-02', null),
-(3755, 1111, default, null),
+    (3755, 1111, '2019-09-02', null),
-(3755, 8888, default, null),
+    (3755, 8888, '2019-09-02', null),
     (3755, 9999, '2017-09-01', 92);
-
--- 查询所有学生信息
-select * from tb_student;
-
--- 查询所有课程名称及学分(投影和别名)
-select couname, coucredit from tb_course;
-select couname as 课程名称, coucredit as 学分 from tb_course;
-
-select stuname as 姓名, case stusex when 1 then '男' else '女' end as 性别 from tb_student;
-select stuname as 姓名, if(stusex, '男', '女') as 性别 from tb_student;
-
--- 查询所有女学生的姓名和出生日期(筛选)
-select stuname, stubirth from tb_student where stusex=0;
-
--- 查询所有80后学生的姓名、性别和出生日期(筛选)
-select stuname, stusex, stubirth from tb_student where stubirth>='1980-1-1' and stubirth<='1989-12-31';
-select stuname, stusex, stubirth from tb_student where stubirth between '1980-1-1' and '1989-12-31';
-
--- 查询姓"杨"的学生姓名和性别(模糊)
-select stuname, stusex from tb_student where stuname like '杨%';
-
--- 查询姓"杨"名字两个字的学生姓名和性别(模糊)
-select stuname, stusex from tb_student where stuname like '杨_';
-
--- 查询姓"杨"名字三个字的学生姓名和性别(模糊)
-select stuname, stusex from tb_student where stuname like '杨__';
-
--- 查询名字中有"不"字或"嫣"字的学生的姓名(模糊)
-select stuname, stusex from tb_student where stuname like '%不%' or stuname like '%嫣%';
-
--- 查询没有录入家庭住址的学生姓名(空值)
-select stuname from tb_student where stuaddr is null;
-
--- 查询录入了家庭住址的学生姓名(空值)
-select stuname from tb_student where stuaddr is not null;
-
--- 查询学生选课的所有日期(去重)
-select distinct scdate from tb_score;
-
--- 查询学生的家庭住址(去重)
-select distinct stuaddr from tb_student where stuaddr is not null;
-
--- 查询男学生的姓名和生日按年龄从大到小排列(排序)
--- asc - ascending - 升序（从小到大）
--- desc - descending - 降序（从大到小）
-select stuname as 姓名, year(now())-year(stubirth) as 年龄 from tb_student where stusex=1 order by 年龄 desc;
-
--- 聚合函数：max / min / count / sum / avg
--- 查询年龄最大的学生的出生日期(聚合函数)
-select min(stubirth) from tb_student;
-
--- 查询年龄最小的学生的出生日期(聚合函数)
-select max(stubirth) from tb_student;
-
--- 查询男女学生的人数(分组和聚合函数)
-select count(stuid) from tb_student;
-select stusex, count(*) from tb_student group by stusex;
-select stusex, min(stubirth) from tb_student group by stusex;
-
--- 查询课程编号为1111的课程的平均成绩(筛选和聚合函数)
-select avg(scmark) from tb_score where couid=1111;
-select min(scmark) from tb_score where couid=1111;
-select count(scid) from tb_score where couid=1111;
-select count(scmark) from tb_score where couid=1111;
-
--- 查询学号为1001的学生所有课程的平均分(筛选和聚合函数)
-select avg(scmark) from tb_score where stuid=1001;
-
--- 查询每个学生的学号和平均成绩(分组和聚合函数)
-select stuid as 学号, avg(scmark) as 平均分 from tb_score group by stuid;
-
--- 查询平均成绩大于等于90分的学生的学号和平均成绩
--- 分组以前的筛选使用where子句
--- 分组以后的筛选使用having子句
-select stuid as 学号, avg(scmark) as 平均分 from tb_score group by stuid having 平均分>=90;
-
--- 查询年龄最大的学生的姓名(子查询/嵌套的查询)
-select stuname from tb_student where stubirth=(
-    select min(stubirth) from tb_student
-);
-
--- 查询年龄最大的学生姓名和年龄(子查询+运算)
-select stuname as 姓名, year(now())-year(stubirth) as 年龄 from tb_student where stubirth=(
-    select min(stubirth) from tb_student
-);
-
--- 查询选了两门以上的课程的学生姓名(子查询/分组条件/集合运算)
-select stuname from tb_student where stuid in (
-    select stuid from tb_score group by stuid having count(stuid)>2
-)
-
--- 查询学生姓名、课程名称以及成绩(连接查询)
-select stuname, couname, scmark from tb_student t1, tb_course t2, tb_score t3 where t1.stuid=t3.stuid and t2.couid=t3.couid and scmark is not null;
-
-select stuname, couname, scmark from tb_student t1 inner join tb_score t3 on t1.stuid=t3.stuid inner join tb_course t2 on t2.couid=t3.couid where scmark is not null order by scmark desc limit 5 offset 10;
-
-select stuname, couname, scmark from tb_student t1 inner join tb_score t3 on t1.stuid=t3.stuid inner join tb_course t2 on t2.couid=t3.couid where scmark is not null order by scmark desc limit 10, 5;
-
--- 查询选课学生的姓名和平均成绩(子查询和连接查询)
-select stuname, avgmark from tb_student t1, (select stuid, avg(scmark) as avgmark from tb_score group by stuid) t2 where t1.stuid=t2.stuid;
-
-select stuname, avgmark from tb_student t1 inner join 
-(select stuid, avg(scmark) as avgmark from tb_score group by stuid) t2 on t1.stuid=t2.stuid;
-
--- 内连接（inner join）：只有满足连接条件的记录才会被查出来
--- 外连接（outer join）：左外连接 / 右外连接 / 全外连接
--- left outer join / right outer join / full outer join
--- 查询每个学生的姓名和选课数量(左外连接和子查询)
-select stuname, ifnull(total, 0) from tb_student t1 left outer join (select stuid, count(stuid) as total from tb_score group by stuid) t2 on t1.stuid=t2.stuid;

更新日志.md

@@ -1,5 +1,17 @@
 ## 更新日志
 
+### 2021年3月28日
+
+1. 最近把数据挖掘的东西梳理了一遍，准备开始写文档啦。
+
+2. 近期收到的打赏通过美团公益捐赠给有需要的人。
+
+    ![](res/donation6.png)
+
+    ![](res/donation7.png)
+
+    ![](res/donation8.png)
+
 ###2020年10月3日
 
 1. 调整项目目录结构。